Field of the Invention
The present disclosure generally relates to display control and, more particularly, to a display control apparatus, a method for controlling the display control apparatus, and a storage medium that stores a related program. More specifically, the present disclosure relates to a technique capable of detecting the position of an object (e.g., a finger or a stylus pen) that contacts a touch screen.
Description of the Related Art
The number of information processing terminals each being equipped with a touch screen is rapidly increasing, recently. The touch screen is usually disposed on a display device and is configured to realize operational feeling as if a user were directly operating a display element. More specifically, the touch screen enables a user to perform an intuitive operation in such a manner that an input target constantly coincides with an operation target. In other words, the touch screen can realize an operation system that is easy to use and is easy to understand.
A conventional touch screen is, for example, capable of measuring an output of a capacitance sensor. If a measurement value exceeds a threshold when an object (e.g., a finger or a pen) has approached an operation surface, the touch screen determines that a touch operation has been performed by the object. Then, the touch screen calculates a coordinate value of the touch position and outputs the calculated coordinate value.
However, at a moment when a user starts physically moving the object away from the operation surface, the touch screen does not immediately stop detecting the contact by the object and does not determine that the touch operation has been cancelled. There is a time lag of several milliseconds before the sensor output becomes smaller than a predetermined threshold. For example, as illustrated in FIG. 9A, when a user moves an object 911 away from a touch screen 900 at a desired position 912, calculation of the touch position continues for a while (e.g., from the position 912 to a position 913) even after the user has cancelled the touch operation. Therefore, in an actual operation, the detection of the object contact terminates at the position 913 where the sensor output becomes smaller than the predetermined threshold. The position 913 is recognized as the position where the touch operation has been cancelled. As a result, for example, in a case where a slider bar 920 is displayed on the touch screen 900 and a slider is movable on the slider bar 920 according to a user touch operation, there will be a problem that the identified position where the touch operation has been cancelled does not coincide with user's intended position.
The present disclosure intends to solve the above-mentioned problem. When a touch operation is performed on the touch screen, the present disclosure prevents a deviation from occurring between a touch position detected according to the touch operation and user's operational feeling.